This invention relates to novel 2-piperazinoalkyl-1-phenylindazol-3-one compounds and salts thereof, and to pharmaceutical compositions containing these compounds. The invention also relates to a method for preparing these compounds, as well as to intermediate products for use in the preparation of these compounds. The preparation of 1-phenyl-2-(3-chloropropyl)-1,2-dihydro-3H-indazol-3-one is known from a work on 1H-indazol-3-ols and 1,2-dihydro-3H-indazol-3-ones by L. Baiocchi et al. (Synthesis, 1978, 633-648).